This invention relates to phase shift apparatus. More particularly, it is concerned with phase shift apparatus in which the amount of phase shift can be varied.
Variable phase shift apparatus of different types which are well-known are useful in many applications. One particular application requiring apparatus with variable phase shifting capability is in the display of graphical information on color television sets. In order to provide different colors throughout the display the color subcarrier frequency must be shifted in phase. It is desirable that the phase shift be variable in response to digital signals accompanying the information to be displayed. Although variable phase shift apparatus has been available for use in this particular application, because of the frequency involved (3.58 MHz is the standard color television subcarrier frequency), it has heretofore been necessary to employ high performance, expensive, components.